After much rancour, placard-waving and hyperbole, this Bill was defeated in the upper house — 25 to 14.

Yes, just in case you missed it, abortion is still illegal in New South Wales, as it is in Queensland.

In NSW, at least, this doesn’t mean abortion is impossible to procure but relies on an interpretation of the Crimes Act 1900, that allows doctors to approve an abortion if a woman’s health is in danger. This includes mental health, as well as social and economic factors. But it does mean that women do not have certain rights — in the ethical sense, at least.

Abortion is a topic that arouses passionate disagreement and furious argument. When such emotions intersect with unreflective beliefs – religious or otherwise – the discussion is rarely reasonable.

The conservative, pro-life position isn’t hard to distill down to a simple argument. The infamously controversial bioethicist, Peter Singer, reckons that at its core it goes something like this:

A human foetus is an innocent human life. It’s wrong to end an innocent human life. So, it’s wrong to end the life of a foetus.

Bam! And the question is settled! The soundness of such reasoning might seem ironclad at a glance — but it isn’t.

At what stage does something become "human life"? Is it indicated by the "quickening"? Does it magically happen at 12 weeks? At eight? At conception? Agreeing on a morally significant line is difficult. Moving the goalposts to something like "potential human life" to avoid the problem just leads to more complications — not least that it rules out all contraception.

Women are under attack & will be charged as criminals, if they have an abortion in NSW. It's very disturbing & naive of the Govt.#auspol 🥀😕 https://t.co/q11lFJaezp

Is it always wrong to end an innocent human life? Plausibly — except euthanasia or assisted suicide (maybe). At a minimum, the argument needs to take consent into account.

What about ending the life of a human being through inaction — such as letting someone starve because you’d rather use your disposable income to buy shoes than donate to a foreign aid organisation? How about buying a Gold Coast apartment while working to dismantle universal healthcare for the poor? There’s a slight inconsistency here, I just can’t put my finger on it. No one expects politicians’ preferences to make sense but hair-splitting about choices versus actions doesn’t stand up to serious scrutiny. The alternative is to believe that the poor – like those selfish enough to be born in countries savaged by war and famine – only have themselves to blame and therefore aren’t innocent. Sound familiar?

This isn’t the worst of the issues that such a simplistic view of abortion faces. Some readers may note that, like our political institutions, there’s a group that’s largely absent from the discussion:

Women.

What about their rights? Does their bodily autonomy not come into it at all? Do they have no say in what physically happens to them?

There is a great analogy that philosopher Judith Jarvis Thompson uses to help illustrate the important of such questions. I’ve embellished it a little for style, but the core idea is still there.

Imagine that you are visiting a hospital to see a sick friend. As you walk in, you don’t notice that you are being watched. You enter a lift with what you think are some hospital staff. One of them consults a photo and then jabs you with a needle. Your consciousness fades.

When you wake up, you are in bed, back to back, with a famous pop star. A doctor explains the situation: The performer has a rare and fatal kidney disease. Some of their more extreme fans have scoured medical records to find a perfect tissue and blood match for them — turns out it’s you. The two of you are connected via your circulatory system and you are now cleaning their blood. If you stay hooked up to them for nine months, they will recover and you can both go on your way. If you unplug now, this celebrity dies.

The doctor, who is pretty grumpy with the kidnappers, won’t force you to go through with it — you must decide.

It’s clear that if you volunteered to stay attached, you are doing something good. But are you obliged to give up nine months of your life to save them? Does the singer’s right to life mean they can use your body for nine months without your consent? That’s a tricky question but a lot of people would say that you have the right to decide what happens to your body, even under these circumstances.

The parallel is this: A foetus may have a right to life but it’s right to life does not necessarily override the right of a woman to withdraw or withhold the use of her body. Given that using someone’s body without their consent is generally seen as a bad thing (rape, kidnapping, slavery and so on) the pro-lifers now have some explaining to do.

Of course, the obvious response is for the conservative side to say that a woman withdrawing the use of her body is exactly the same as actively killing the foetus and that Thompson and I have just engaged in progressive semantic trickery.

But if not doing something that leads to the end of life is morally equivalent to causing death, we come back to a previous conundrum — where withdrawing foreign aid is the same as actively killing people by starving them. Make no mistake, this is the contradiction that sits at the centre of the conservative attitudes to abortion, one that many people intuitively detect.

Until politicians on the right acknowledge this contradiction, the status quo that devalues women’s right to decide what happens to their bodies will remain. I don’t see this intellectual confrontation happening anytime soon. Progress won’t come from conservatives changing their minds but it might come from voters changing who governs.